Proficiency testing in the USA


CLIA legislation forces certain obligations on labs in the USA.  Unlike the EU, ISO 17025 / 15189 accreditation is not one of them.  Proficiency testing is: and so it should be.

Testing labs with External Quality Assurance (EQA) samples rather than accrediting their record-keeping reveals that US labs fail to detect around 1 in 20 pathogens.  It’s much less burdensome and much more efficient and informative.  Knowing a figure like this allows you to estimate the confidence you have in a lab’s results.  It’s unlike the vague motto of UKAS, “Delivering Confidence,” which delivers only a delusion of confidence.

ISO accreditation relies on operationalising the rather abstract concept of quality so that it can me measured.  Sort of.  It is capable of binary measurement only: compliance or non-compliance.  No ability to measure the tolerance of accreditation.  Stupid isn’t it?  Or maybe that is the point of it.  Accreditation demands precision but cannot be measured itself.  A crafty way to avoid this defunct approach exposing its inadequacy.

We’re still waiting for an analogous publication of UK External Quality Assurance schemes that reveals if UKAS/CPA accrediation improves performance. 

Will there be any difference significant enough to justify accreditation’s survival?

Read the abstract of the US investigation:

Pathogen Detection in Food Microbiology Laboratories: An Analysis of Proficiency Test Performance

C. C. Snabes1, D. C. Edson1, S. Empson1, L. D. Massey2;
1American Proficiency Inst., Traverse City, MI, 2N/A, Pomona, MO.

Background: For U.S. clinical laboratories, proficiency testing (PT) has evolved into an essential component of quality assurance programs. These laboratories are regulated by CLIA 1988, which requires participation in an approved PT program. Food laboratories may soon be subject to similar requirements with the passage of the Food Safety Modernization Act into law on January 4, 2011, which may mandate food laboratory accreditation for foods regulated by the FDA. American Proficiency Institute, a federally approved PT provider serving the clinical laboratory market, and an A2LA Accredited Food Microbiology PT provider, offers PT programs for the food industry. This study includes data from 1999 to 2012. Our objective was to assess whether laboratories have improved in their ability to detect or rule out contamination over a 14 year period with 4 common food pathogens: E. coli O157:H7, Salmonella spp., Listeria monocytogenes, and Campylobacter spp. Methods: False (+) and false (-) rates for selected food microbiology pathogens were recorded from cumulative proficiency testing results submitted in 3 test events per year over 14 years. Results: Performance accuracy for food pathogens remains problematic although the recent trend shows a decrease in both false positive and false negative results. The average percentage of false (+) results over the past 14 years has averaged 2.5 % for E. coli O157:H7, 3.9 % for Salmonella spp.; 2.5 % for L. monocytogenes; and 3.6 % for Campylobacter spp. The average percentage of false (-) results over the past 14 years has averaged 6.6 % for E. coli O157:H7; 4.9 % for Salmonella spp.; 5.7 % for L. monocytogenes; and 9.1 % for Campylobacter spp. Conclusions: In this retrospective study involving more than 39,500 results, food laboratories continue to routinely fail to detect pathogens in food samples more than 5% of the time. The data suggest that: 1) laboratories are more proficient at ruling out than detecting the presence of pathogens, and 2) cumulative performance is showing an encouraging trend downward in false positive and false negative rates over a 14 year period.

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One Response to Proficiency testing in the USA

  1. Hi there! great post. Thanks for sharing some very interesting and informative content it is a big help to me as well, keep it up!!!

    Proficiency Testing

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